feat(client): 节点 status=down 在列表置灰+「不可用」+禁选(#7 客户端侧)

#7 服务端已在 agent 离线时把节点判 down,但客户端 Node 模型没读 status、
列表照常显示。补:Node.status 字段 + 解析 /v1/nodes 的 status;ServerTile/
_NodeGridTile 在 isDown 时 Opacity 置灰 + 末尾「不可用」+ onTap 禁用。全平台
共享(lib/widgets+screens)。up 节点 Opacity 1.0 无变化,golden 不动。加 down
状态 widget 测试。

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

client/lib/widgets/server_tile.dart

@@ -43,33 +43,43 @@ class ServerTile extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     final c = context.pangolin;
+    final down = node.isDown; // 节点不可用(agent 离线):置灰 + 「不可用」+ 禁选。
+    final unavail = lang == AppLang.zh ? '不可用' : 'Unavailable';
     return InkWell(
-      onTap: onTap,
-      child: Container(
-        color: active ? c.accentSubtle : Colors.transparent,
-        padding: const EdgeInsets.symmetric(horizontal: 14, vertical: 12),
-        child: Row(
-          children: [
-            CountryCode(code: node.code, active: active),
-            const SizedBox(width: 13),
-            Expanded(
-              child: Column(
-                crossAxisAlignment: CrossAxisAlignment.start,
-                children: [
-                  Text(node.localizedName(lang),
-                      style: PangolinText.sm
-                          .copyWith(color: c.fg1, fontWeight: FontWeight.w600, fontSize: 15)),
-                  const SizedBox(height: 2),
-                  Text(node.localizedSub(lang),
-                      style: PangolinText.caption.copyWith(color: c.fg3, fontWeight: FontWeight.w400)),
-                ],
+      onTap: down ? null : onTap,
+      child: Opacity(
+        opacity: down ? 0.55 : 1.0,
+        child: Container(
+          color: (active && !down) ? c.accentSubtle : Colors.transparent,
+          padding: const EdgeInsets.symmetric(horizontal: 14, vertical: 12),
+          child: Row(
+            children: [
+              CountryCode(code: node.code, active: active && !down),
+              const SizedBox(width: 13),
+              Expanded(
+                child: Column(
+                  crossAxisAlignment: CrossAxisAlignment.start,
+                  children: [
+                    Text(node.localizedName(lang),
+                        style: PangolinText.sm
+                            .copyWith(color: c.fg1, fontWeight: FontWeight.w600, fontSize: 15)),
+                    const SizedBox(height: 2),
+                    Text(node.localizedSub(lang),
+                        style: PangolinText.caption.copyWith(color: c.fg3, fontWeight: FontWeight.w400)),
+                  ],
+                ),
               ),
-            ),
-            Text(node.pingLabel, style: PangolinText.mono.copyWith(color: c.fg2, fontSize: 12)),
-            const SizedBox(width: 8),
-            SignalBars(ping: node.ping),
-            if (active) ...[const SizedBox(width: 10), Icon(PangolinIcons.check, size: 18, color: c.accent)],
-          ],
+              if (down)
+                Text(unavail,
+                    style: PangolinText.caption.copyWith(color: c.danger, fontWeight: FontWeight.w600, fontSize: 12))
+              else ...[
+                Text(node.pingLabel, style: PangolinText.mono.copyWith(color: c.fg2, fontSize: 12)),
+                const SizedBox(width: 8),
+                SignalBars(ping: node.ping),
+                if (active) ...[const SizedBox(width: 10), Icon(PangolinIcons.check, size: 18, color: c.accent)],
+              ],
+            ],
+          ),
         ),
       ),
     );